Production of baker's yeast by biotechnology

Bakers' yeast can rightly be considered one of the oldest products of industrial fermentation. Even today, it is one of the most important products of biotechnology, both in terms of quantity (over 2.5 million tonnes annually) and function (the qualities of yeast-raised bread are recognized worldwide, transcending national and cultural boundaries).

For biochemists and geneticists, its importance goes far beyond its place in the food industry and its role in bread-making. Indeed, Saccharomyces cerevisiae, the species to which baker's yeast belongs, has been and still is one of the most widely used model organisms in university research laboratories for biochemical, physiological and genetic studies: it is the simplest eukaryote (eukaryote : differentiated cell containing a nucleus; man, like yeast, is a eukaryote); it grows rapidly, doubling every two hours, is easy to manipulate in the laboratory, and its age-old use in fermented foods is a guarantee of its safety.

Most of our knowledge of the physiology and genetics of "Saccharomyces cerevisiae" has been acquired in university laboratories on so-called laboratory strains, which Carlos Gancedo [1] humorously calls "Saccharomyces laboratorii". These strains, better suited to genetic analysis than industrial strains, have growth rates and fermentative activity levels well below those of yeast strains used by the fermentation industry. As a result, this knowledge cannot be used directly and must be transposed to industrial strains and industrial yeast conditions. Scientific advances have enabled significant progress to be made in the control of cultures in fermenters, product stabilization by gentle drying (i.e. in a fluidized bed, enabling 80% of fermenting power to be retained), for example, and the construction of new strains better adapted to the eating habits encountered in user countries and to the constraints linked to the evolution of baking techniques.

Bakers' yeast is therefore both a traditional product and one that is constantly evolving.